what's in my IP packet - structure & parsing - wireshark to the rescue
- make a small UDP server - using the lowlevel functionality of your hardware
- do a tcp handshake : preserving state of a connection
(ipv4 only for now, will have a look at ipv6)
HTTP 101
- using web services (post your sensor data to a webserver)
abusive DHCP client - make your network suffer a bit

saturday-evening:

practical use of some environmental sensors to control & monitor
your mushroom-grow chamber
Monitoring: Pachube/ sensors, Controling the enviroment with relays.

TLDR: How to set up an scale. Home made calibration
Hygrometer: Fix the frequency in order to get the right results.
Set up the PCB final design (Fritzing :s ?).
***1 Proposed Initial code, incremental code (steps) & final code.
Call for buying missing Nanodes (also maybe to offer to sell the ones that people dont use)